This invention relates to barrier apparatus for a passageway or throughway, be it an internal or external roadway for vehicles or an internal or external pathway for pedestrians.
Roadway barrier apparatus is known which comprises a barrier element in the form of a chain extending across the roadway between a pair of vertically slotted housings, one to each side of the roadway. One housing contains a drive mechanism which comprises a drum-like pulley rotatably driven by the output shaft of a reduction-geared motor that is positionally fixed at or near the base of the housing, one end of the chain being coiled around the drum. The apparatus further comprises, adjacent the top of the one housing, a positionally fixed pulley wheel over which the chain passes before traversing the roadway and being secured to an anchor point located inside the opposite housing and adjacent its top. When the motor is operated to wind in the chain about the drum, the barrier element adopts a raised position in which it extends across the roadway between the two housings, and its exposed length is commensurate with the distance between the two housings. As the motor is operated to unwind the chain and to lower its exposed part to a slack position or relaxed condition, the length of the exposed part of the chain is increased until (most of) it lies loosely over the surface of the roadwayxe2x80x94or, possibly in a channel cut in the roadway to accommodate it. However in this relaxed condition, or as it approaches it, the chain adopts a curved path in the vicinity of the arris between each housing and the roadway, and it can be easily deflected and damaged by or cause damage to passing vehicles or, if used as a barrier apparatus for a pedestrian pathway, cause pedestrians to trip and fall and/or cause injury to them. Such difficulties or disadvantages are not fully overcome even if the roadway is provided with a channel to accommodate the chain. Furthermore if such a channel is provided, it can in any event give rise to additional problems associated with the collection therein of water, dirt and debris.
It is therefore considered desirable to provide throughway barrier apparatus which can overcome the above-mentioned and/or other difficulties or problems associated with the prior art.
According to one aspect of this invention there is provided throughway barrier apparatus comprising: a pair of housings to be sited one to each side of a throughway, each housing being provided with an upstanding surface of magnetic material; a movable device including a magnetic body which is magnetically coupled to the upstanding surface and which has a cylindrical surface in rolling contact with the upstanding surface; and drive means to move the magnetically coupled device upwardly and downwardly of the surface; and further comprising: a barrier element to extend across the throughway, the barrier element being in use connected to the two said movable devices for movement therewith.
Preferably the barrier element is a flexible element, e.g. chain, cable or the like.
It will be appreciated that the length of the barrier element between the two devices is thus kept substantially constant as the two devices and the barrier element move up and/or down, and there is no substantial change in the element""s effective length.
Preferably each movable device and its associated drive means is provided internally of a respective said housing, a coupling unit in use connects between an associated said movable device and an adjacent end of the barrier element, said coupling unit including a member to extend through an upstanding elongate aperture (e.g. a slot) in said upstanding surface.
Preferably each drive means comprises a motor unit movable together with said movable device.
Advantageously, each motor unit has a counterweighting mechanism associated therewith to provide a countering load to at least the weight of the movable motor unit.
Preferably each said movable device comprises a magnetic body which (a) has radial end walls at opposed ends of said outer cylindrical surface, (b) is magnetically polarised axially of the cylindrical surface, and (c) has a disc-like pole plate at each radial end of the cylindrical surface, the two disc-like pole plates having a like diameter greater than the diameter of the cylindrical surface.
Advantageously each motor unit is provided with a drive shaft (preferably of square or other non-circular cross-section) that is a loose fit within a bore of like cross-sectional shape extending through the magnetic body of said movable device.